Barry Eisler’s website is a treasure cove of information. He has listed all of his Rain novels and the order that they were published here.
In the gallery, Mr. Eisler has photos arranged by books. You can start with the very first Rain novel, A Clean Kill in Tokyo, and open the gallery of photos. There are photos that were taken from various locations in Tokyo that were used as a back drop for various parts of the book.
Keanu usually does extensive research for his characters and projects and there is no reason to expect his preparation for Rain to be any different. Mr. Eisler’s location photos for his novels may give a good feel for the types of locations that they are scouting for the TV show.